Evaluating the Effect of Composite States on the Understandability of UML Statechart Diagrams

Summary:
Statecharts are an effective way of expressing the behaviour of a software system. This paper evaluated the effect of composite states on the understandability of UML statechart diagrams. To do this the authors conducted two experiments. The second was a replica of the first.

Experiment Design
The authors used 55 fourth year computer science students for the experiment. The replica study used 178 computer science students (their experience was not included in the description). The participants were presented with two diagrams, one was a statechart and the other wasn't. They were then asked to answer question about understandability.

Results
"The results of the experiment confirm that the use of composite states improves the understandability of the diagrams, so long as the subjects of the experiment have had some previous experience in using them."